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    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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    <script>
        // 声明常量const+常量名
        const PI=3.1415926
        console.log(PI);
        //不允许更改值
        // PI=3.14
        // console.log(PI);
        // 常量声明时必须赋值
        // const page
        

    </script>
</body>
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